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Amos Keag wrote: Maybe my terms are not up to date. My electrical service connection is 3 wire 240 volts AC at 60 Hz. Within the distribution panel RED is connected to one feed; BLACK is connected to the other feed and white is connected to the common connection [return]. The common connection is then distributed throughout the house as the bare wire in standard wiring. The common, white and return, connection is connected to an external earth connection [ground] by an 8 foot ground rod.. So, the WHITE wire serves as return for both RED and BLACK circuits and has a single earth connection. So, your 3 prong socket contains connections to power as follows: HOT [either RED or BLACK] circuit, RETURN [WHITE] and GREEN [GROUND] [supposedly zero current carrying. A GFI works on this part of the connection]. In the ASTRON RS 35 the primary wiring has the GREEN connected to the chassis. The BLACK/WHITE go to the transformer primary. This is fine. Yes, that's all fine, and per code. In US wiring terminology, the green wire is "ground". It's present entirely for safety purposes - it's not supposed to carry any current back to the panel during normal operation. It carries current only in the event of a fault. It's what the external chassis should be tied to, for metal-chassis equipment with a three-wire cord. Black is "hot". I'm told that this color was chosen because black is traditionally the color of death. White is "neutral". It's the current return for the hot supply. It should never be tied to the chassis, for two reasons: [1] The occasional hot/ground reversal thanks to an mistake in the house wiring. You really don't want your chassis floating at 120 VAC above local ground. [2] The neutral pin at the outlet can be pulled several volts above ground voltage, if some load on that circuit is drawing a healthy number of amperes, due to I^2*R drop in the house wiring. If the chassis were tied to neutral, and this occurred, someone might manage to get a shock if they touched both the chassis and a truly-grounded pipe or wire. With a nearby lightning strike that blew the utility 3 phase transformer and affected approximately 50 consumers there are several possible causes of trouble. Among these are imbalance in utility service [i.e. the 240 into the house becomes seriously imbalanced] a lightning induced magnetic transient that couples to all ground loops, or my system was still connected to antennas and power. I had ALL connections to antennas and power plugs removed except the 1/2 inch copper pipe earth connection at the service panel. My neighbors lost garage door openers, multiple tv sets, numerous telephone circuits, numerous internet circuits, COMCAST had to rewire approximately 1/4 mile of cable tv in front of the house, several homes lost expensive stereo and sound lab setups. In my house all ground fault interuptors activated. And two circuits in my PRO II exploded to charcoal with dust and stench. The LAN blew up, and one computer was lost. Ouch! My condolences! When a strike of that magnitude occurs nearby, I have a feeling that the Law of Chaos prevails. The current will do whatever it (censored) well wants to. Even some equipment which is entirely unplugged might take enough of a pulse via induction to suffer some damage to sensitive components. Glad to hear that you managed to recover the cost of replacement! -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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